Mercury is one of the most interesting planets, and whether you believe me or not now, you will after this. Mercury is the closest planet to the sun and is 57,000,000 KM away from the sun. now that Pluto is a subplanet it is now the smallest planet too at 4876 KM in Diameter. Mercury, unlike most of the other planets, has no moons at all. It goes around the sun once every 88 days, but spins in a circle once every 58 days. One wacky fact is that even though it is the closest to the sun it is not the hottest.external image dn8928-1_600.jpgYes, Mercury is the closest planet to the sun, but it is not the hottest because venus has an extreme greenhouse effect that keeps all of the heat it gets trapped inside.

Mercury has a thin atmosphere made up of Hydrogen and Helium. Most scientists believed that Mercury had a thicker atmosphere but solar winds blew it away because it was so close to the sun. Mercury's mass is about 330,220,000,000,000,000,000,000 kg. The average density on Mercury is 5.43 grams per cubis centimeter. Mercury has three layers, It has a core, a mantle, and a crust. The core of the planet has cooled completely so now it is a cool solid iron core.external image mercury-nsf-browse.jpg The escape Velocity on Mercury is 15,450 km/h. Mercury is considered to have "wrinkles". Whe the planet's molten core cooled down it contracted making cliffs and caters on mercury, in other words giving it wrinkles.
Mariner 10 is the only space probe to go to Mercury. It went by twice in 1974 and once in 1975. It took pictures of some of the surface of Mercury.